Shakespearean sonnet themes explore the ideas of love, aging, beauty, time, lust, practical obligations, and feelings of incompetence. These themes emerge from Shakespeare's descriptions of the relationships between his characters. They are also evident in his use of narrative language and explanations of the speaker's internal feelings. Additional Shakespearean sonnet themes include the struggle between what collective society is willing to accept and an individual's desires.
Within Shakespeare's poetry is the idea that beauty disappears with time, making a person less desirable and somewhat depressed about his own existence. The idea behind one of the most prolific Shakespearean sonnet themes is that children should be born to maintain beauty. Since the ability to maintain an ideal physique and set of appealing looks is impossible, the only hope is to create the next generation that will inherit those features. Time is seen as an enemy to vitality, value, and physical identity.
Another of the Shakespearean sonnet themes focuses on the idea of conflict between real love and simple sexual desire. In the poet's view, there is often confusion between which is which. Lust can disguise itself as love and is easily mistaken for it. A temptation exists to pursue that which is visually enticing, rather than taking the time to discover genuine feeling.
Shakespeare also explores the idea that love or feelings of love can be harmful. In the language of his poetry, the author describes the emotional and physical effects of being involved in romantic relationships. Disease is one of the consequences, in addition to the negative feelings of isolation that occur upon separation. There is also the risk of vulnerability by being in a romantic relationship, since the individuals' lives, decisions, and self-concepts become dependent upon one another.
Within Shakespearean sonnet themes is the use of symbols. Some of those include stars, trees, flowers, and weather. For example, the recurrent symbol of weather and seasons is used to communicate the turbulent nature behind human feeling. Relationships often go through the same type of cycles that weather patterns do, which Shakespeare clearly illustrates in the language of some of his verses.
The symbol of stars is used by the author to communicate the idea of destiny. Rather than accepting the idea that destiny is predetermined, Shakespeare explores the idea of an individual's ability to create his own fate. Flowers and trees represent the delicate nature of life and beauty. In some ways, possessing beauty obligates a person to have children and ensure a more favorable set of circumstances for future generations.